Scilab Function
Last update : 13/12/2005

Sgrayplot - smooth 2D plot of a surface using colors

### Calling Sequence

  `Sgrayplot(x,y,z,<opt_args>)`
  `Sgrayplot(x,y,z [,strf, rect, nax, zminmax, colminmax, mesh, colout])`

### Parameters

- `x,y`: real row vectors of size n1 and n2.
- `z`: real matrix of size (n1,n2). `z(i,j)` is the value of the surface at the point (x(i),y(j)).
- `<opt_args>`: This represents a sequence of statements `key1=value1,key2=value2`,... where `key1`, `key2,...` can be one of the following: strf, rect, nax, zminmax, colminmax, mesh, colout (see `plot2d` for the 3 first and `fec` for the 4 last).
- `strf,rect,nax`: see `plot2d`.
- `zminmax, colminmax, mesh, colout`: see `fec`.

### Description

`Sgrayplot` is the same as `grayplot` but the plot is smoothed. The function `fec` is used for smoothing. The surface is plotted assuming that it is linear on a set of triangles built from the grid (here with n1=5, n2=3):

                 _____________
                 | /| /| /| /|
                 |/_|/_|/_|/_|
                 | /| /| /| /|
                 |/_|/_|/_|/_|

The function `colorbar` may be used to see the color scale.

The parameter `zminmax` is useful for animation purpose (see an example after) and the parameter `colminmax` lets the user choose a part of the current colormap (see the `fec` help page).

Enter the command `Sgrayplot()` to see a demo.

### Examples

    // example #1
    x=-10:10; y=-10:10;m =rand(21,21);
    clf()
    xset("colormap",hotcolormap(64))
    Sgrayplot(x,y,m, strf="011", rect=[-20,-20,20,20])

    // example #2
    t=-%pi:0.1:%pi; m=sin(t)'*cos(t);
    clf()
    xset("colormap",jetcolormap(64))
    colorbar(-1,1)
    Sgrayplot(t,t,m, strf="041")

    // example #3: an animation display cos(t)*sin(x)sin(y).
    // (Remark: this animation uses the old mode)
    n = 30;
    nt = 100;
    x = linspace(0,2*%pi,n);
    y = linspace(0,%pi,n/2);
    z = sin(x')*sin(y);
    t = linspace(0,4*%pi,nt);
    xselect(); clf()
    f=gcf();
    f.color_map=jetcolormap(64);
    f.pixmap='on';
    colorbar(-1,1)
    Sgrayplot(x,y,cos(t(1))*z, strf="042", zminmax=[-1,1])
    c=gce(),e=c.children
    xtitle("Kaa''s eyes")
    for i = 1:nt
       e.data(:,3)=matrix(cos(t(i))*z,-1,1);
       show_pixmap()
    end
    f.pixmap='off';

### See Also

`fec`, `fgrayplot`, `grayplot`, `Sfgrayplot`, `colorbar`,

### Author

J.Ph.C.